Lithium salt unleashes 93% retention breakthrough in sodium-ion battery tech

Researchers in Korea have developed a method to significantly improve the cycle stability and capacity retention of sodium-ion batteries (SIBs) by adding lithium hexafluorophosphate (LiPF6) to the battery electrolyte. This innovation resulted in a battery retaining 92.7% of its capacity after 400 charge-discharge cycles, a notable improvement over the typical 80% retention seen in similar SIBs. The lithium salt additive enhances the formation of a robust solid electrolyte interphase (SEI) layer on the hard carbon anode, which is less soluble and reduces electrolyte decomposition, thereby protecting the anode. Additionally, lithium ions partially dope the surface of the O3-type cathode, creating “Li-ion pillars” that reinforce the cathode’s layered structure and reduce gas evolution during cycling. This dual-action process—anode protection and cathode reinforcement—was confirmed through electrochemical mass spectrometry and microscopy, showing reduced CO2 evolution and preserved electrode structures. The scalable synthesis